Method of masking photographic color images



Patented Aug. 15,1950

I was) :sTATEs oF Fi-cE Richard V. Young, Rochester,f3N. Y. assignor toEastman Kodak Company,?Rochester, N. Y., a corporation ofNewJersey NoDrawing. ApplicationJulyi'it,1947,

Serial No. 758,990 y 1 Claim.

This invention relates to photography and particularly to'a method ofmasking photographic color images. v v

It is knownthatdyesused in subtractive multicolpnphotographic picturesdo 1 not transmit all of the light which theoretical-1 considerationsdemand. The cyan dye which shouldabsorb red light and "transmit greenand bluelight usually absorbs a small amount ofgreen and blue-light aswell-es a-major proportion of red light. The magenta dye which shouldabsorb green light an'ditransmit blue an red light usually absorbs aconsiderable amount of blue light and a small amount of red light. Theyellow dye which should absorb blue light and transmit green and redlight is more generally satisfactory although sometimes it absorbs asmall amount of green light. The result of printing a multl-colorpicture formed of such dyes is to introduce unequal parts of all threecolor records in each image which is made regardless of the color oflight which is used in printing or the sensitivity of the printingmaterial employed. Correction of the colors during printing is thereforedesirable and this is usually done by masking as described in priorpatents such as Evans U. S. Patent 2,203,653 and Hanson U. S. Patent2,294,981.

In order to avoid the difficulty of registering the masking image withthe picture image, it is desirable to have the mask integral with thecolor picture images. A method of producing an integral colored maskinvolving the use of colored couplers in a color coupling process isdescribed in Hanson U. S. application Ser. No. 533,910, filed May 3,1944, now Patent No. 2,449,966 of September 21, 1948. According to themethod of the Hanson application, azo dye derivatives of couplers areused which are destroyed wherever a dye image is formed by colorcoupling.

I have found a method by which masking images may be produced in aphotographic emulsion layer containing color developed dye images, themask being colored as required by theoretical considerations and beingintegral with the picture image.

According to my invention a single layer or multi-layer photographicfilm having color couplers in the emulsion layer or layers is exposedand developed to negative color images by development with a primaryaromatic amino developing agent. This produces the usual azomethine orindaniline dyes in the emulsion layers, leaving residual silver halideand uncoupled coupler in the unexposed portions of the layers. The filmis then flashed or uniformly exposed and deprior patents andpublications.

dye f masking images in *.the residual 1 portions of the layers. 1

The use of aromatic 'hy'drazines gas photo-5 graphic developing agentshas been suggested: in Woodward and McQueen 2,339,213 describes 'the useof aromatic hydrazinesltodevelop a colored image in a photographic"layer by :combining with phenolic or active methylene compounds iofithetype used as color ='couplers. The reaction of "the "hydrazinedeveloper'is suchthat during development of a silver halidethe'hydrazineis oxidized to a diazonium salt which reacts with the couplerin the layer to form an azo dye.

The coupler which I use in the red-sensitive layer of a multi-layerphotographic film will be a phenol or naphthol derivative which yields acyan indaniline or indophenol dye but which produces a red or orange azodye by coupling with the hydrazine developer. The orange or red dyeshould absorb the blue and green light which the cyan dye shouldtransmit and thus affect a masking or color correction of the cyan dyeimage in the well-known manner.

Similarly, the green-sensitive layer of the photographic element willcontain a color coupler such as a cyano acetyl or pyrazolone derivativewhich yields a magenta azo methine dye but which produces a yellow azodye with the hydrazine developer. The yellow dye will compensate for theblue light absorption of the magenta 'dye by maintaining constant bluelight absorption through the magenta layer.

Suitable aromatic hydrazines which may be used as developing agentsaccording to my invention are phenyl hydrazine, p-phenylchlorohydrazine, p-nitro phenyl hydrazine, 2,4-dinitro hydrazine, a-naphthylhydrazine and b-naphthyl hydrazine.

My invention will be more clearly understood by reference to thefollowing specific example.

A multi-layer photographic film containing couplers such as described inJelley and Vittum U. S. Patent 2,322,027 is exposed to an image orobject and color developed in a primary aromatic amino developer such asthat disclosed on page 5 of Jelley and Vittum Patent 2,322,027. The filmis then washed andpflashed with white light and developed in a hydrazinedeveloper of the following composition:

Grams Phenyl hydrazine 2 to 10 Sodium carbonate 20 Water to 1 liter.

red-sensitive layer and developing it in a suitable hydrozine developerand then repeating the procedure with the green-sensitive layer and de-'veloping it in a second hydrazine developer. This method affords a moresatisfactory method of controlling the composition of the masking dyeformed in the two layers since it is not always possible to obtain amask dye of a satisfactory color with a single hydrazine developingagent.

Where I refer to color couplers, it will be understood that I refer tothe usual phenolic, naphtholic, or active methylene couplers which formindophenols, indaniline or azomethine dyes by coupling with thedevelopment product of a primary aromatic amino developing agent such aspara-phenylenediamine, para-aminophenol, or their derivatives.

I claim:

The method of producing a color correcting image in a multi-layerphotographic film having a silver halide emulsion layer sensitive to thered spectral region and containing a color coupler capable of producinga cyan dye, a silver halide emulsion layer sensitive to the greenspectral region and containing a color coupler capable of producing amagenta dye, and a silver halide emulsion layer sensitive only to theblue spectral region and containing a color coupler capable of producinga yellow dye, all of said dyes being formed by coupling with thedevelopment product of a primary aromatic amino developing agent, saidmethod comprising exposing said film to an object, developing negativesilverand dye images therein by treating said layers with a primaryaromatic amino developing agent, exposing said red-sensitive layer withred light and said greensensitive layer with green light, developingsaid layers after each exposure of said green-sensitive andred-sensitive layers with a different aromatic hydrazine to form a redto orange positive azo dye image in the red-sensitive layer and a yellowpositive azo dye image in the green-sensitive layer, and allowing saidnegative dye images and said positive azo dye images to remain in saidfilm.

; RICHARD V. YOUNG.

REFERENCES CITED.

The following references are of record in the file of this patent:

UNITED STATES PATENTS Woodward et al. Jan. '11, 1944

